With the advent of high-resolution stereoscopic displays, a desirable function is a cursor that is positionable within three dimensions, as opposed to the conventional two-dimensional (2-D) cursor. A conventional 2-D cursor, when viewed with stereo images, appears to lie in only one image plane. This is unsatisfactory in that a viewer is given confusing depth cues. A further problem with the use of a 2-D cursor is that the viewer may only reference points along a display x-axis and y-axis, but not along the display z-axis (depth).
The following U.S. patents are cited as showing various stereoscopic display systems and/or the use of a 3-dimensional cursor.
In U.S. Pat. No. 4,214,267, issued Jul. 22, 1980, entitled "Stereofluoroscopy System", to Roese et al. there is described a mechanism for generating a 3-dimensional cursor composed of two dots which may be displaced horizontally with respect to one another. The 3-dimensional cursor is said to read out a distance that may be sent to an external numerical readout.
In U.S. Pat. No. 4,562,463, issued Dec. 31, 1985, entitled "Stereoscopic Television System with Field Storage for Sequential Display of Right and Left Images" to Lipton there is described a stereoscopic television system that employs, for viewing, electro-optical occluding shuttered spectacles.
In U.S. Pat. No. 4,808,979, issued Feb. 28, 1989 entitled "Cursor for Use in 3-D Imaging Systems" to DeHoff et al. there is described a cursor image that is said to include depth cue features to assist an observer in gauging the depth of a position being indicated. The cursor image is displayed on a CRT in left and right perspective projections of differing binocular disparity which are used by the observer to form a 3-dimensional image of the cursor. The cursor is said to include depth cues that continuously vary along the length of a tether symbol so as to allow the observer to properly register the position of the cursor within the 3-dimensional space.
In U.S. Pat. No. 4,835,528, issued May 30, 1989, entitled "Cursor Control System" to Flinchbaugh there is described the control of a two-dimensional, as opposed to a three-dimensional, cursor in three-dimensions.
In U.S. Pat. No. 4,987,527, issued Jan. 22, 1991, entitled "Perspective Display Device for Displaying and Manipulating 2-D or 3-D cursor, 3-D Object and Associated Mark Position" to Hamada et al. there is described cursor control in a system that positions a robot in three-dimensions.
In U.S. Pat. No. 4,791,478, issued Dec. 13, 1988, entitled "Position Indicating Apparatus" to Tredwell et al. there is described a system for producing a stereoscopic image of a scene that includes an object. Overlay generators superimpose on the image a stereoscopic image of a cursor. The cursor is said to vary in position, size, and appearance. This is accomplished by providing two separate channels, one for the left eye and one for the right eye. The two channels are preserved along an entire signal path from source to display. As a result, two separate monitors are required to view the cursor. That is, this patent does not provide left and right images that are shown sequentially on a single monitor.
Also of interest are the following two U.S. patents that teach the combining of images onto a common color display. Specifically, U.S. Pat. No. 4,599,611, issued Jul. 8, 1986 entitled "Interactive Computer-Based Information Display System," and U.S. Pat. No. 4,317,114, issued Feb. 23, 1982, entitled "Composite Display Device for Combining Image Data and Method".
What is not taught by these U.S. patents, and what is thus one object of the invention to provide, is novel circuit apparatus, and a method of using same, for displaying a 3-dimensional cursor upon a display, the cursor being provided with both stereoscopic and monoscopic depth cues.